Effects of Inlet Boundary Conditions On Spiral Casing Simulation

The Hölleforsen hydropower plant is situated on the river Indalsälven in Sweden and consists of three Kaplan turbines units with a total installed capacity of 50 MW at the operational head of 27 m. The main task of this research work is to simulate the flow through the penstock, spiral casing and distributor (guide vanes and stay vanes) of the Hölleforsen model. Numerical simulations are performed on the model with 1:11 scale of the prototype turbine, a runner diameter of 500 mm, a runner speed of 595 rpm and a volume flow rate of 0.522 m3/s at the head of 4.5 m. Flow in the penstock and spiral casings are very complex with several flow phenomena; separation, turbulence and unsteadiness, due to the viscosity, boundary conditions and complexity in the geometry. To gain information on the flow characteristics, numerical simulation of the complex three-dimensional turbulent viscous flow through the penstock, spiral casing and distributor of the turbine is performed. Conservation mass and momentum equations of the flow are analysed using finite volume method with the software ANSYS CFX10.0. The objectives are to study the effects of inlet boundary conditions and also t